Heat treatment apparatus

ABSTRACT

Heat treatment apparatus for heating the internal surface of a metal pipe has an adjustable frame which is adapted for insertion within the pipe for variation in length perpendicular to the axis of the pipe. A pneumatic motor is drivably connected to a rotatable supply pipe for a combustible gaseous medium mounted within the adjustable frame. Radial supply pipes extend perpendicular from the rotatable supply pipe and carry heaters at their radially outer ends. Combustible gaseous medium supplied to the rotatable supply pipe is thus burnt in the heaters as the heaters are rotated within the metal pipe, to obtain circumferentially uniform heating of the metal pipe.

O United States Patent 91 u 11 3,887,328 Maddock June 3, 1975 HEAT TREATMENT APPARATUS Primary Examiner-J0hn J. Camby [76] Inventor: Paul Thomas Maddock, 92 Amwen Attorney, Agent, or firm-Woodhams, Blanchard &

Hill, Pontardawe, Swansea, Flynn Glamorganshire, England 221 Filed: Feb. 4, 1974 ABSTRACT [21] Appl, No; 439,330 Heat treatment apparatus for heating the internal surface of a metal pipe has an adjustable frame which is adapted for insertion within the pipe for variation in [30] Fol-mg Apphc au0n Pn0my Dam length perpendicular to the axis of the pipe. A pneu- 1973 Umted Kingdom 6129/73 matic motor is drivably connected to a rotatable supply pipe for a combustible gaseous medium mounted CL 432/224; 266/23 K; 266/23 M within the adjustable frame. Radial supply pipes ex- [5 Cl. tend perpendicular from the rotatable supply and l Field Search 432/224, 266/23 carry heaters at their radially outer ends. Combustible 266/23 M gaseous medium supplied to the rotatable supply pipe is thus burnt in the heaters as the heaters are rotated References Cited within the metal pipe, to obtain circumferentially uni- UNITED STATES PATENTS form heating of the metal pipe.

2,058,388 l0/l936 Rendleman 266/23 M 3,675,905 7 1972 Placek 432/225 7 Clams 2 Drawing HEAT TREATMENT APPARATUS BACKGROUND OF THE INVENTION The invention relates to heat treatment apparatus for the internal surface of a metal pipe.

Where metal pipes have to be joined by butt welding, it is often necessary, particularly with large crosssection pipes such as those forming the walls of waterborne oil rigs, to pre-heat the pipe metal prior to welding or to anneal the welded pipe metal to relieve stresses induced during welding. Although heating may be applied to the exterior of a pipe to be treated this results in the dissipation of a considerable amount of energy into the external surroundings and so it is preferred to heat the pipe internally.

In the past, the internal heating has been carried out with a circular radiant heater which is mounted centrally within the pipe to be treated by means of three or more radially extending stays which engage the internal surface of the pipe. Variation in heating, for pipes having different wall thicknesses, is controlled by varying the supply of combustible gaseous medium supplied to the heater because the heater is always located at a fixed distance from the internal surface of the pipe by the radially extending stays. Not only is this method of control cumbersome, it also tends to accentuate the major disadvantage of this method of heat treatment.

With this method of heat treatment, it has been found that the flames and gaseous products of combustion tend to heat the upper part of the pipe to a greater extent than the lower part, because of convection. This leads to very unsatisfactory heat treatment. Moreover, as it is necessary to vary the rate of burning to vary the heating of the pipe, the disproportionate heating of the upper part of the pipe also varies and is difficult to control or compensate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide heat treatment apparatus which is capable of heating the internal surfaces of a metal pipe in a more uniform and controlled manner than has hiterto been possible.

According to the invention, there is provided heat treatment apparatus for heating the internal surface of a metal pipe, comprising at least one heater, such as a radiant heater, mounted at one end of a radial supply pipe for a combustible gaseous medium, the radial sup ply pipe extending perpendicularly from the axis of a rotatable supply pipe which is alignable with the axis of the metal pipe.

Preferably, the radial supply pipe is of telescopic construction so as to allow adjustment of the heater for heating the internal surfaces of pipes of different diameters and may thus include a socket portion which is clamped to the rotatable supply pipe and extends equally on both sides of the rotatable supply pipe and an inner portion which extends from one end of the socket portion and is of the same length as the socket portion, the rotatable supply line being communica tively connected to the radial supply pipe by means of a branch pipe connected to the other end of the socket portion of the radial supply pipe.

With apparatus such as this, the or each heater may be held in very close proximity to the internal surface of the pipe so as to ensure much more radiant heating of this surface. The extent of heating can be controlled by varying the duration of heating and the speed of the or each heater as it rotates within the pipe. The rotatable supply pipe may be disposed below the axis of the metal pipe so that any convective heating of the upper part of the pipe may be counterbalanced by greater radiant heating of the lower part of the pipe.

Conveniently, the rotatable supply pipe is mounted in an adjustable frame which is capable of variation in length perpendicular to the axis of the rotatable supply pipe and, in a preferred construction, the adjustable frame has two rectangular ends supported by telescopic legs and bearing spring loaded wheels which are engageable with the internal surface of the pipe so as to allow axial movement of the frame along the metal pipe.

Each rectangular end may be supported at its corners by telescopic legs which each have at least two telescopically connected portions and clamps for locking each co-operating pair of inner and outer portions.

With a conventional clamp having an adjusting screw which passes through an aperture in the outer portion of a co-operating pair of inner and outer portions of a telescopic leg into engagement with the inner portion, there is a tendency for the adjusting screw to deform the external surface of the inner portion and so reduce the ease with which the inner portion slides within the outer portion. This defect may be avoided by ensuring that each clamp includes a locking pad accommodated within a recess formed internally of the ring for engagement with the inner end of the adjusting screw and extending through an aperture formed in the outer portion of the telescopic leg for locking engagement with the inner portion of the telescopic leg, the locking pad having an inner surface which is complementary to the external surface of the inner portion.

To reduce the possibility of inadvertent ignition of combustible gaseous medium within the metal pipe, for example: as a result of arcing between components of an electric motor, the rotary drive of the rotatable sup ply pipe may be provided by a pneumatic motor. The adjustable frame may therefore support a housing which encloses a pneumatic motor, a reduction drive connecting the pneumatic motor to the rotatable supply pipe, and bearings supporting the rotatable supply pipe.

In this construction, a mixing chamber may be mounted within the housing on one end of the rotatable supply pipe and connected to two inlet pipes provided with regulating valves for supplying, respectively, a gaseous fuel and oxygen to the rotatable supply pipe and it is possible that one of the gaseous media supplied to the mixing chamber may be first passed through the pneumatic motor to provide the rotary drive.

DESCRIPTION OF THE DRAWINGS A heat treating apparatus according to the invention is hereinafter described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic perspective view of the apparatus, and

FIG. 2 is an end view of a clamp forming part of the apparatus.

DESCRIPTION OF A PREFERRED EMBODIMENT As shown in FIG. 1, two heaters 17, such as gas burners, are mounted on two radial supply pipes 15A, 15B projecting perpendicularly from a rotatable supply pipe 10, for rotation within metal pipes 21 and 22 to heat the metal in the region of the junction between these two pipes. The rotatable supply pipe 10 is aligned with the axes of the pipes 21 and 22 and supported in bearings 7 and 11 mounted in a housing 30 (only partly shown) forming part of an adjustable frame 23 which is supported for axial movement along the pipes 21 and 22 on wheels 18.

Compressed air fed through a line 3 is fed to a pneumatic motor 4 provided with an integral reduction drive 5 and a pinion 9A mounted on the output shaft (not shown) of the reduction drive 5 meshes with a gear wheel 98 to provide a further speed reduction. The gear wheel 9B is non-rotatably connected to the rotatable supply pipe 10 so as to be rotatable by the pneumatic motor 4.

Compressed air and propane are fed through pipes 1A and 2A provided with regulating valves 1 and 2 to a mixing chamber 6. The open end of the rotatable sup ply pipe 10 is enclosed by the mixing chamber 6 and a seal (not shown) prevents leakage of gas from the mixing chamber 6 around the outside of the rotatable supply pipe 10.

The combustible gaseous mixture is thus fed through the rotatable supply pipe 10 into a manifold chamber 12 and, through branch lines 13A and 138 provided with stop valves 14A and 148, to the ends of two socket portions 15A of the radial supply pipes carrying the heaters 17. The two socket portions 15A are carried in a clamp 10A at the end of the rotatable supply pipe 10 and extend equally on opposite sides of the clamp 10A. Inner portions 158 of the radial supply lines, which are communicatively connected to the burners 17, are slideable in the socket portions 15A and secured in position by compression glands 16 which co-operate with silicone rubber O-rings (not shown). A further silicone rubber O-rings (not shown) is mounted between the inner end of each inner portion 158 and the enclosing socket portion 15A. The combustible gaseous mix ture fed to the burners 17 can therefore be burnt to provide radiant heating and the speed of rotation of the burners may be varied between 0 and 12 rpm. so as to control the extent of heatingv In a typical construction, the socket portion 15A and the inner portion 158 of the radial supply pipe are both 2 feet in length so that the heat treating apparatus is capable of heating pipes which vary substantially in diameter.

The supporting wheels 18 of the adjustable frame 23 are mounted at opposite ends of two leaf springs 18B which are mounted at axially opposite ends of rectangular ends 23A of the adjustable frame 23 and the four corners of each end 23A are supported by telescopic legs 24A, 24B, 24C which are connected to the housing 30 by means of brackets 31 and plates 32 (only partly shown).

As shown in FIG. 2, each clamp for locking together each co-operating pair of inner and outer portions 24A, 248 or 24B, 24C of each telescopic leg of the adjustable frame 23 has a ring 25 which is secured to the outside of the outer portion 24A (as shown in FIG. 2) by means of a locking screw 26A and secured to the inner portion 243 (as shown in FIG. 2) by means of an adjustment screw 268 which extends in screwthreaded engagement through a radial aperture formed in the ring 25 into abutment with a locking pad 27 which is accommodated in a recess 28 formed internally of the ring 25. The locking pad 27 has an inner surface 27A which is complementary to the external surface of the portion 248 and extends through an aperture 29 formed in the outer portion 28.

Having described my invention, I claim:

1. Heat treatment apparatus for heating the internal surface of a metal pipe, comprising a rotatable supply pipe for a gaseous fluid which is alignable with the axis of the metal pipe, at least one radial supply pipe for the gaseous fluid extending perpendicularly from the axis of the rotatable supply pipe, a heater mounted at one end of the radial supply pipe, the radial supply pipe being of telescopic construction and having a socket portion which is clamped to the rotatable supply pipe and extends equally on both sides of the rotatable supply pipe and an inner portion which extends from one end of the socket portion and is of substantially the same length as the socket portion, and a branch supply pipe connected between the other end of the socket portion of the radial supply pipe and the rotatable sup- P y P p 2. Heat treatment apparatus according to claim 1, in which an adjustable frame which is capable of variation in length perpendicular to the axis of the rotatable supply pipe supports the rotatable supply pipe.

3. Heat treatment apparatus for heating the internal surface of a metal pipe, comprising a rotatable supply pipe for a gaseous fluid which is alignable with the axis of the metal pipe, at least one radial supply pipe extending perpendicularly from the axis of the rotatable supply pipe, a heater mounted at one end of the radial supply pipe, and adjustable frame means supporting thereon the rotatable support pipe and capable of variation in length perpendicular to the axis of the rotatable supply pipe, said adjustable frame means having two rectangular ends supported by telescopic legs and bearing spring loaded wheels which are engageable with the internal surface of the metal pipe so as to allow axial movement of the frame means along the metal pipe.

4. Heat treatment apparatus according to claim 3, in which each rectangular end of the adjustable frame means is supported at its corners by four telescopic legs which each have at least two telescopically connected portions and clamps for locking each co-operating pair of inner and outer telescopically connected portions.

5. Heat treatment apparatus according to claim 4, in which each clamp comprises a ring surrounding an outer portion of a telescopic leg, an adjustment screw in screw-threaded engagement with a radial aperture through the ring, a locking pad accommodated in a recess formed internally of the ring for engagement with the inner end of the adjustment screw and extending through an aperture formed in the outer portion of the telescopic leg for locking engagement with the cooperating inner portion of the telescopic leg, the locking pad having an inner surface complementary to the external surface of the inner portion.

6. Heat treatment apparatus for heating the internal surface of a metal pipe, comprising a rotatable supply pipe for a gaseous fluid which is alignable with the axis of the metal pipe, at least one radial supply pipe extending perpendicularly from the axis of the rotatable supply pipe, a heater mounted at one end of the radial supply pipe, and adjustable frame means supporting thereon the rotatable and capable of variation in length perpendicular to the axis of the rotatable supply pipe, the adjustable frame means supporting a housing which on one end of the rotatable supply pipe and connected to two inlet pipes provided with regulating valves for supplying, respectively, a gaseous fuel and oxygen to the rotatable supply pipe. 

1. Heat treatment apparatus for heating the internal surface of a metal pipe, comprising a rotatable supply pipe for a gaseous fluid which is alignable with the axis of the metal pipe, at least one radial supply pipe for the gaseous fluid extending perpendicularly from the axis of the rotatable supply pipe, a heater mounted at one end of the radial supply pipe, the radial supply pipe being of telescopic construction and having a socket portion which is clamped to the rotatable supply pipe and extends equally on both sides of the rotatable supply pipe and an inner portion which extends from one end of the socket portion and is of substantially the same length as The socket portion, and a branch supply pipe connected between the other end of the socket portion of the radial supply pipe and the rotatable supply pipe.
 1. Heat treatment apparatus for heating the internal surface of a metal pipe, comprising a rotatable supply pipe for a gaseous fluid which is alignable with the axis of the metal pipe, at least one radial supply pipe for the gaseous fluid extending perpendicularly from the axis of the rotatable supply pipe, a heater mounted at one end of the radial supply pipe, the radial supply pipe being of telescopic construction and having a socket portion which is clamped to the rotatable supply pipe and extends equally on both sides of the rotatable supply pipe and an inner portion which extends from one end of the socket portion and is of substantially the same length as The socket portion, and a branch supply pipe connected between the other end of the socket portion of the radial supply pipe and the rotatable supply pipe.
 2. Heat treatment apparatus according to claim 1, in which an adjustable frame which is capable of variation in length perpendicular to the axis of the rotatable supply pipe supports the rotatable supply pipe.
 3. Heat treatment apparatus for heating the internal surface of a metal pipe, comprising a rotatable supply pipe for a gaseous fluid which is alignable with the axis of the metal pipe, at least one radial supply pipe extending perpendicularly from the axis of the rotatable supply pipe, a heater mounted at one end of the radial supply pipe, and adjustable frame means supporting thereon the rotatable support pipe and capable of variation in length perpendicular to the axis of the rotatable supply pipe, said adjustable frame means having two rectangular ends supported by telescopic legs and bearing spring loaded wheels which are engageable with the internal surface of the metal pipe so as to allow axial movement of the frame means along the metal pipe.
 4. Heat treatment apparatus according to claim 3, in which each rectangular end of the adjustable frame means is supported at its corners by four telescopic legs which each have at least two telescopically connected portions and clamps for locking each co-operating pair of inner and outer telescopically connected portions.
 5. Heat treatment apparatus according to claim 4, in which each clamp comprises a ring surrounding an outer portion of a telescopic leg, an adjustment screw in screw-threaded engagement with a radial aperture through the ring, a locking pad accommodated in a recess formed internally of the ring for engagement with the inner end of the adjustment screw and extending through an aperture formed in the outer portion of the telescopic leg for locking engagement with the co-operating inner portion of the telescopic leg, the locking pad having an inner surface complementary to the external surface of the inner portion.
 6. Heat treatment apparatus for heating the internal surface of a metal pipe, comprising a rotatable supply pipe for a gaseous fluid which is alignable with the axis of the metal pipe, at least one radial supply pipe extending perpendicularly from the axis of the rotatable supply pipe, a heater mounted at one end of the radial supply pipe, and adjustable frame means supporting thereon the rotatable and capable of variation in length perpendicular to the axis of the rotatable supply pipe, the adjustable frame means supporting a housing which encloses a pneumatic motor, a reduction drive connecting the pneumatic motor to the rotatable pipe and bearings supporting the rotatable supply pipe. 